adjective
spontaneous
spahn-TAY-nee-uhs/spɑːnˈteɪniəs/
Happening naturally without planning or outside prompting.
The spontaneous dance interrupts an ordinary walk home.

Etymology
The Latin adjective meant acting of one's own free will. English extended this idea to actions and events arising from an internal impulse rather than external prompting; the underlying word for will has uncertain origins.
In context
prop usage can be spontaneous or can be pre-planned using a prop in a manner other than intended is one of the best ways to get a laugh
More examples
- They made a spontaneous trip to the beach.
- Her laughter was warm and spontaneous.
- The scientist recorded spontaneous changes in the sample.
Forms
spontaneous
spontaneity noun — natural action without planning
spontaneously adverb — without planning or prompting
Similar words
- unplanned
- Not arranged beforehand, without necessarily arising naturally.
- impulsive
- Done on a sudden urge, sometimes without enough thought.